For many years, it has been known to dispense liquids such as soaps, sanitizers, cleansers, disinfectants, and the like from a dispenser housing maintaining a removable and replaceable cartridge containing the liquid. The pump mechanism employed with such dispensers has typically been a liquid pump, simply emitting a predetermined quantity of the liquid upon movement of an actuator. Recently, for purposes of effectiveness and economy, it has become desirable to dispense the liquids in the form of foam, generated by the interjection of air into the liquid, generating the formation of bubbles thereby. Accordingly, the standard liquid pump has given way to a foam generating pump, which necessarily requires means for combining the air and liquid in such a manner as to generate the desired foam. However, foam generating pumps are more expensive than liquid dispensing pumps, necessarily increasing the cost of disposable cartridges that include the pump with each cartridge.
Typically, foam pumps include an air compressor portion and a fluid passing portion—the two requiring communication to ultimately create the foam. The portion required for compressing the air is not given to wear and degradation to the extent of the portion required for passing the liquid and generating the foam from the combination of liquid and air. Accordingly, it has been determined that there is no necessity for replacing the air compressor, but only the liquid pumping and foam generating portion of the pump when replacement of the cartridge is necessary. Accordingly, a bifurcation of the pump has been determined to be possible and desirable.